9. Pemeriksaan protein dan enzim

Protein dan Enzim
KIMIA KLINIK
Rochmy Istikharah

Clinical Significance

Clinical Significance

?

α-helix
β-sheet

Peptid
e bond

pH
Ionic strength
Temperature
Solvent (dielectric
constant)

Hormone receptors
Antibodies
Coenzymes

Denatura
tion

Electrophoresis
Isoelectric focusing

Ion-exchange chromatography

Clinical Significance
CONCENTRATION
♮ Total protein concentration
6-8 g/dL
♮ Selected protein conct.

PATTERN


Depend on
protein
propertie
s

Selected Protein
Analysis

Normal condition

8% albumin glycosylated
nonenzymatically

Hyperglycemia
(e.g. Diabetes Mellitus)
up to 25%
albumin glycosylated
nonenzymatically

Related with HbA1c in DM


Useful for assessing
diabetic control in
Px with hemolytic

Total Protein Analysis

Total Protein Analysis


OH

Cu2+ + Protein  Cu2+-Protein complex
≥ 2 peptide bonds
Less sensitive than Lowry

!

Protein Analysis
•• Skrining

Skrining
•• Total
Total protein
protein 6-8
6-8 g/dL
g/dL dengan
dengan 3,5-5
3,5-5 g/dL
g/dL albumin
albumin
•• Pattern
Pattern of
of serum
serum protein
protein in
in agarose
agarose electrophoresis
electrophoresis
(Serum
(Serum protein

protein electrophoresis:
electrophoresis: SPE)
SPE)

Able to
diagnose

Unable to
diagnose
Selected
Protein
Analysis

Methods: Protein
Elektroforesis
Prinsip: Pemisahan protein berdasarkan perbedaan
muatan &/atau bobot molekul
(metode standar elektroforesis)
Protein Serum Elektroforesis


pI: isoelectric point (ampholyte & net charge = 0)

Horizontal electrophoresis
Cth. Agarose electrophoresis

Vertical electrophoresis
Cth. SDS-PAGE

Automated electrophoresis

Plasma Protein
Elektroforesis

SPE Patterns/Serum
PEP
Modified from
Vithoulkas H. HomeoNews
2008;9:9-10

SPE Patterns

Modified from
Vithoulkas H. HomeoNews
2008;9:9-10

SPE Patterns
Modified from
Vithoulkas H. HomeoNews
2008;9:9-10

IgA 

SPE Patterns
Modified from
Vithoulkas H. HomeoNews
2008;9:9-10

Large spike in γ region
Homogenous Ig

immunofixation electrophoresis


O’Connel et al. Am Fam Physician
2005;71(1):105-112

McPherson & Pincus
Henry’s Clinical Diagnosis
21st Ed. 2006

Enzym
e

Kimia Klinik
Rochmy Istikharah

ENZIM
Glossary


Proenzim (Zymogen)




Enzim



Holoenzim



Apoenzim



Koenzim/kofaktor



Isoenzim


Plasma & Non-plasma
Specific Enzymes
Plasma
• Normal ada di plasma
Plasma adalah tempat
aksinya

Non-plasma
• Plasma bukan tempat
aksinya

• Konsentrasinya tinggi
dibanding organ

• Konsentrasinya di
plasma rendah (normal
krn sel apoptosis)

• Cth. Enzim pd
koagulasi


• Konsentrasi
meningkat???
• Apoptosis, nekrosis,
obat, etc

Harper’s
Biochemistry
26th Ed

• Regenerasi &
penyimpanan ATP

Kreatin + ATP
CK

Mg2+

Kreatin fosfat + ADP

• CK-BB: (CK-1)brain
type
• CK-MB: (CK2)hybrid type
• CK-MM: (CK3)Muscle type

Anderson, J. L. et al. J Am Coll Cardiol 2007;50:652-726
Copyright ©2007 American College of Cardiology Foundation. Restrictions may apply.

Faktor yg mempengaruhi
nilai rentang enzim
• Waktu sampling
• MI: CK-MB: 6 jam
• Usia
• Gender:
massa otot,
olahraga,
konsentrasi hormon
• Ras
• Olahraga

Alkaline phosphatase
(U/L)
[AMP buffer, p-nitrophenyl
phosphate substrate,
30oC]
18 th

40 – 100

CK serum
30 – 50 U/L
500 - 1000 U/L

Pengukuran Konsentrasi
Enzim
Pengukuran Tidak
Langsung:
aktivitas enzim
1.Single reaction
Pengukuran produk
atau substrat yg
dikatalisis oleh
enzim tsb  jarang
2.Coupled reaction

Pemeriksaan
Langsung:
Immunoassay

• Monoclonal/polyc
lonal antibodies
• Mengukur
konsentrasi enzim itu
sendiri
• Contoh teknik: ELISA

• Suhu
• Suhu dijaga dlm rentang ±0,1o
• Perbedaan 10o  aktivitas enzim meningkat 2xnya
• pH: pH optimum utk enzim aktif
• Garam
• Terlalu tinggi  aktivitas enzim turun drastis
• Konsentrasi protein:
• Plasma manusia, protein: 70 g/L; Urin hampir tidak ada
• Penambahan albumin pd pemeriksaan amilase di urin
(spike)
• Inhibitor & pengganggu lain